Brandon Mendoza
Oct. 28, 2014
Chapter 8 Notes
1. Define communications including connectivity, the wireless revolution, and
communication systems.
Communications is the process of sharing data, programs, and information between two
or more computers. Connectivity means you can connect your PC to other PCs and
information sources almost anywhere. The wireless revelation is the use of mobile or
wireless devices like smartphones and tablet PCs. The revolution is the support of more
than just the wireless telephone. Today’s mobile devices support e-mail, web access and
other internet applications. Many devices can and will connect to one another without any
physical connection. Communication systems has four basic elements, Sending and
receiving devices, Connection devices, Data transmission specifications, and
Communication channel.
2. Discuss communication channels including physical connections (twisted-pair, coaxial,
and fiber-optic cable) and wireless communications (Bluetooth, Wi-Fi, microwave,
WiMax, LTE, satellite, and infrared).
Communication channels carry data from one computer to another. The two categories of
communication channels are Physical Connections and Wireless Connections. Physical
connections include Twisted-pair cable which are pairs of copper wire twisted together.
Both telephone lines and Ethernet are twisted pair. Ethernet cable consists of twisted pair
cable; slowest; being phased out by more advanced and reliable media. Coaxial cable is a
single solid copper core it has 80 times transmission of twisted pair, television and
computer networks Fiber optic transmits as pulses of light through tiny tubes of glass.
More secure and reliable, they are the best over limited distances they are lighter, more
reliable, and faster than coaxial cable. Wireless connections do not use a solid substance
to connect it uses the air itself. Most use radio waves to communicate. Types of wireless
connections are Bluetooth, short range radio communication standard, 33 ft, wireless
headsets, printer connections, hand held devices. WiFi, wireless Fidelity communicates
over short distances. Microwave, uses high-frequency radio waves, WiMax Worldwide
Interoperability for microwave Access, allows greater distances for Wi-Fi. LTE (long
term evolution), newest wireless standards. Similar to WiMax but promises to provide
greater speed and quality in the near future. Satellite, uses satellites orbiting about 22,000
miles above the earth as microwave relay stations; many of these offered by Intelsat, the
International Telecommunications Satellite Consortium which is owned by 114
governments and forms a worldwide communications system
Uplink, sending data to a satellite. Downlink, receiving data from a satellite GPS (Global
Positioning system), use a network of 24 satellites owned and managed by the Defense
Department which continuously sends location information to earth. Infrared, Light
waves used over short distances. Sometimes called line of sight communications,
Sending and receiving devices must be in clear view of one another.
3. Discuss connection devices including modems (telephone, DSL, cable, and wireless
modems) and connection services (DSL, ADSL, cable, satellite and cellular connection
services).
Modem is short for modulator-demodulator. The types of modems are Telephones, DSL
(digital subscriber line) which uses standard phone lines to create a high speed connect.
ASDL (asymmetric digital subscriber line) which is one of the most widely used types of
DSL Cable which uses same coaxial cable as television. And wireless also known as
WWAN modem.
4. Discuss data transmission including bandwidths (voiceband, medium band, broadband,
and baseband) as well as protocols (IP addresses, domain name servers, and
packetization).
Bandwidth is a measurement of the width or capacity of the communication channel. It
means how much information can move across the communication channel in a given
amount of time. There are four types, Voiceband also known as low bandwidth. Standard
phone line which is too slow for many types of transmissions especially high-quality
video the typical speeds are 56 to 96 kbps. Medium band with special leased lines to
connect minicomputers and mainframes as well as to transmit data over long distances
(for larger computer systems). Broadband which is used for high-capacity transmissions
(DSL, cable, satellite connections) and specialized high-speed devices that effectively
transmit high-quality video and other communication needs and its typically 1.5 mbps.
And Baseband which is widely used to connect individual computers that are located
close to one another.
5. Discuss networks by identifying and defining specialized terms that describe computer
networks.
A computer network is a communication system that connects two or more computers so
that they can exchange information and share resources. Nodes (key term) any device
connected to a network. Client (key term) a node that requests and uses resources from
other nodes. Server (key term) a node that share resources with other nodes. Directory
server (key term) – specialized server that manages resources. Host (key term) computer
system that can be accessed over a network. Router (key term) node that forwards or
routes data packets. Switch (key term) central node that coordinates the flow of data.
These tasks used to be performed by a hub (key term). Network interface cards (NIC)
(key term) expansion card that connects a computer to a network. Network operating
system (NOS) (key term) control activities of all computers on the network. Network
administrator (key term) computer specialists responsible for network operations.
6. Discuss network types including local area, home, wireless, personal, metropolitan, and
wide area networks.
Local area networks - LANs (key term) Computers and devices linked in distances of
less than a mile. Linked by cable. Benefits are for economy and flexibility. With network
gateways (key term) , LANs can be connected to other LANs or any other type of
network. Ethernet (key term) is one standard for connecting network nodes together.
Home Networks (key term) – LANs are now being commonly used by individuals in
home/apartments; allow different computers to share resources including a common
Internet connection; can be connected by various means including a wireless LAN
(WLAN) Wireless LAN (key term) – wireless local area network. All communications
pass through the network’s centrally located wireless access point (key term) or base
station (key term) Hotspot (key term) is a wireless access point that is open to the public.
Personal Area networks (key term) – works within a very small area. Connects cell
phones to headsets, PDAs to other PDAs, keyboards to cell phones, etc. MANs
(metropolitan area network) (key term) –span distances up to 100 miles. Network linking
nodes and resources within the geographical bounds of a city. WANs (wide area
networks) (key term) - Countrywide and worldwide networks use microwave relays and
satellites to reach users and Internet is the widest WAN.
7. Define network architecture including topologies (bus, ring, star, tree, and mesh) and
strategies (client/server and peer-to-peer).
Network topology is the physical layout. Bus network is where each device is connected
to a common cable called a bus or a backbone. Ring Network (key term) all
communications travel along a ring. The most commonly used today are the star, tree and
mesh. Network Architecture (key term) describes how a network is arranged and how
resources are coordinated and shared.
8. Discuss organization networks including Internet technologies (intranets and extranets)
and network security (firewalls, proxy servers, intrusion detection systems, and virtual
private networks).
Intranet is a private network within an organization and Extranet is a private network that
connects more than one organization.